The invention concerns a device for sharpening knives, shears or similar cutting tools with at least one abrasive sharpening element which is located in a housing withdrawing against spring force.
Devices for sharpening knives, shears, or similar cutting tools are known in very different designs. In addition to ceramic sharpening disks and sharpening stones, sharpening steels are used in particular for knife sharpening, and indeed, also in the home. Since, in particular, the sharpening of knives with sharpening stones or sharpening steels requires a certain manual skill, special knife sharpeners, which primarily are used in private homes, also have been developed.
DE 38 33 065 C2 discloses a knife sharpener which includes two sharpening pieces in the form of sharpening disks mounted capable of turning, parallel and offset from one another, in a plastic housing, which disks can draw back spring-mounted. The knife cutting edge to be sharpened is inserted from above into the slot formed by the circular sharpening pieces transverse to the length of the housing and moves with the application of a pressure force relative to the sharpening pieces.
Although such knife sharpeners have proved themselves in practice, they have the disadvantage that they are suited only for keeping knives sharp by regular sharpening. Dull knives, the cutting edge of which has become too thick as a result of insufficient resharpening and incorrect handling, can be restored to the functional condition (sharpness) only with considerable expenditure of time, or in part can no longer be restored.
The object of the invention is to cremate a sharpening device of the type mentioned above, which makes a simple sharpening of knives, shears, or similar cutting tools possible with avoiding the above-mentioned disadvantages, in particular if these cutting tools have a cutting edge deviating from a straight edge.
The achievement of this object by means of the invention is characterized by the fact that the sharpening element is made in the shape of a strip and is located on a blade-shaped carrier which for its part is guided spring-mounted on the housing.
The strip-shaped design of the sharpening element and the arrangement thereof on a strip-shaped carrier guided spring-mounted on the housing produces the possibility of guiding the cutting edge of the cutting tool at the desired sharpening angle relative to the sharpening element, the motion including components passing both in the longitudinal direction of the sharpening element and also transverse to this. Because of the spring-mounted guiding of the sharpening element on the housing, the sharpening element is in a position to draw back within limits, so that the sharpening surface matches the existing cutting geometry of the cutting tool. In this way cutting tools also can be sharpened reliably with a cutting edge deviating from a straight line, in particular of a concavely or convexly curved cutting edgexe2x80x94also with a curvature changing along the cutting edge.
According to a further feature of the invention the blade-shaped carrier is guided spring-mounted at least on its ends, in each case via a spring on the housing, which results in a particularly simple construction.
According to a further development of the invention, in each case the blade-shaped carrier can be made as a part molded on one end of the strip-shaped sharpening element, which part is guided spring-mounted in the housing in each case via a spring. This design results in a particularly simple configuration.
In the case of an alternative embodiment of the invention, the blade-shaped carrier is mounted on the housing and made as a spring element. In the case of this design there are no additional springs, so that the number of components is reduced.
Independent of the configuration of the carrier, the invention also proposes making the working surface of the strip-shaped sharpening element convex transverse to its length. This produces a better adjustment of the working surface of the sharpening element to a cutting element deviating from a straight line.
In the case of a preferred embodiment of the device according to the invention, several sharpening elements are guided spring-mounted on the housing parallel to and separated from each other in each case via a carrier. A number of sharpening elements of this kind shortens the time expenditure required for sharpening a cutting tool, without hindering the possibility of adjusting the individual sharpening elements to the cutting edge geometry in each case, since each sharpening element is guided spring-mounted on the housing independent of the others.
If cutting tools also are to be sharpened with a so-called cylindrical grinding with the device according to the invention, according to a further feature of the invention the working surfaces are made corresponding in cross-section to the cylindrical grinding of the respective cutting edge. The spring-mounted sharpening elements also make it possible to move this cutting edge geometry transverse to the longitudinal axis of the sharpening elements.
Further with the invention it is proposed to mount each strip-shaped sharpening element with its ends in each case on a tongue-shaped carrier and to combine several tongue-shaped carrier into one carrier unit, which can be installed in the housing as a component. This results in the possibility of creating an assembly including the cutting elements which can be used in housings of different designs.
In the case of a further development the carrier unit is mounted capable of turning on a base plate, which in each case is provided with guides for the free ends of the tongue-shaped carrier, in order to avoid buckling or other damage to the latter.
In order to improve the mobility of the sharpening elements for the purpose of adapting to the respective cutting edge geometry of the cutting tool to be sharpened, the sharpening elements in each case can be made elastically springmounted between their ends in each case mounted on a tongue-shaped carrier. In this case the elasticity of the sharpening elements is added to the elastic properties of the tongue-shaped carrier.
In order to prevent damage to the sharpening elements on the basis of their elastic deformation, the elastic deformation of the sharpening elements can be limited in each case by a stop. This stop preferably is made in the middle of the carrier unit.
Altogether the invention results in a device for sharpening cutting tools of this kind, which makes a reliable sharpening of cutting tools possible in spite of its simply and inexpensively made construction, even if these cutting tools have a cutting edge geometry deviating from a straight line.